In motor drive vehicles, it is known that the sound generated from a motorcycle is low. In order to notify that a vehicle is approaching, it is preferable that the sound generated from the motorcycle be louder like a gasoline engine. Thus, an automobile on which a sound emission device is mounted (vehicle approach notification device) that generates simulation sound or the like is disclosed (for example, refer to FIG. 11 of Patent Document 1).
As shown in FIG. 11 of Patent Document 1, an electric vehicle (31) (numerals in parentheses show reference numerals described in Patent Document 1; the same hereinbelow) includes a motor drive unit (32) and travels using the power of the motor. Additionally, the electric vehicle (31) is equipped with a sound emission device (3) including an amplifier (16), sound emission control means (12), and the like, and emits sound from a speaker (17) according to a vehicle speed.
However, in the electrical sound emission device (3), in order to generate sound, electric power is consumed, and the parts of the amplifier (16) and the sound emission control means (12) are required. Thus, a sound emission device that does not require electric power is also proposed (for example, refer to FIG. 1 of Patent Document 2).
As shown in FIG. 1 of Patent Document 2, in the sound emission device, winds are collected by an air collection pipe (1), and the collected winds blow on an end of a U-shaped pipe (4) to generate sound.
As the air collection pipe (1) has a large diameter, a large amount of winds can be collected. However, it is difficult in terms of space to mount the large-diameter air collection pipe (1) on a small vehicle, such as a motorcycle.
That is, a vehicle approach notification device, which is compact, efficient, and suitable for a motorcycle or the like, taking into consideration a reduction in power consumption or the number of parts, is required.
Additionally, when the speaker (sound emission device) is attached to a two-wheeled electric vehicle or the like with a little surplus space as compared to a four-wheeled vehicle, a very large speaker cannot be applied. Therefore, even in a case where a relatively small speaker is used, an arrangement in which a high notification effect is obtained is desired.
Moreover, in the case of a two-wheeled vehicle or the like, there are limitations to setting the speaker apart from the rider, and the balance between a reduction in audibility to the rider and the volume of notification to the surroundings that is the original purpose is difficult, an improvement in such a point is also anticipated.